4.2 A : Graphing Quadratics in Vertex and Intercept Form

• Graphing Quadratics in VERTEX FORM• Y = a(x- h)² + k• Vertex is (h,k) (↔ opposite, ↕)• Axis of symmetry is x = h (x = x of vertex)• a> 0 (positive) opens up• a < 0 (negative) opens down• IaI = stretch or shrink• Use TRANSFORMATIONS to graph!

Examples: Graph. Id vertex, axis of symmetry & max or min

• 1. y = 2(x+1)² - 8

• 2. y = -(x-1)² + 5

• 3. y = ½ (x-3)² - 4

Graphing quadratics in Intercept (Factored) Form

• INTERCEPT (factored) form• Y = a(x – p)(x – q)– X-intercepts= opposites of #’s in parenthesis– Vertex X value = – Vertex Y value = Put Vertex X value into original

for all x’s & evaluate– Axis of symmetry: x= Vertex x value ()

Examples: graph. Id x-intercepts, vertex, axis of symmetry & max/min

• 4. y = (x – 3) (x – 7 )

• 5. f(x) = 2(x – 4 ) (x + 1 )

• 6. y = - ( x + 1) (x – 5 )